The present invention relates to an electronic endoscope system, an electronic endoscope processor, and a method of acquiring blood vessel information for acquiring information on a blood vessel from an image acquired by an electronic endoscope and producing an image from the acquired information.
In recent years, the field of medicine has been seeing a number of diagnoses and treatments using electronic endoscopes. A typical electronic endoscope is equipped with an elongated insertion section that is inserted into a subject's body cavity. The insertion section has therein incorporated an imager such as a CCD at the tip thereof. The electronic endoscope is connected to a light source device, which emits light that, leaving the tip of the insertion section, illuminates the inside of a body cavity. With the inside of the body cavity illuminated by light, the subject tissue inside the body cavity is imaged by an imager provided at the tip of the insertion section. Images acquired by imaging undergo various kinds of processing by a processor connected to the electronic endoscope before being displayed by a monitor. Thus, the electronic endoscope permits real-time observation of the images showing the inside of the subject's body cavity and thus enables sure diagnoses.
The light source device uses a white light source such as a xenon lamp capable of emitting white broadband light whose wavelength ranges from a blue region to a red region. Use of white broadband light to illuminate the inside of a body cavity permits observing the whole subject tissue from acquired images thereof. However, although images acquired by broadband light illumination permit generally observing the whole subject tissue, there are cases where such images fail to enable clear observation of subject tissues such as extremely small blood vessels, deep-layer blood vessels, pit patters, and uneven surface profiles formed of recesses and bumps. As is known, such subject tissues may be made clearly observable when illuminated by narrowband light having a wavelength limited to a specific range. As is also known, image data obtained by illumination with narrowband light yields various kinds of information on a subject tissue such as oxygen saturation level in a blood vessel.
For example, JP 2001-37718 A describes a device wherein a blood information amount calculator calculates a blood information amount in a subject and a region setting unit sets a given region of an endoscopic image whereupon a simulated image data generator uses the information on the specified region and the calculated blood information amount to produce simulated image data that permits recognition of its quantitative change, and an image synthesizer combines the produced simulated image data with the endoscopic image to produce and output synthesized data.
JP 2648494 B describes illuminating with near-infrared narrow-band light IR1 and IR3 whose vascular absorbances change according to oxygen saturation level and a near-infrared narrowband light IR2 whose vascular absorbance does not change in order to acquire an image each time different light is emitted. Then, images acquired by illuminating with narrowband light IR1 and IR3 whose vascular absorbances change and an image acquired by illuminating with narrowband light IR2 whose vascular absorbance does not change are used to calculate variations in luminance between the images, whereupon the calculated variations in luminance are incorporated in the images in monochrome or simulated color. The image thus produced provides information on an oxygen saturation level in a blood vessel.